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28 Cards in this Set
- Front
- Back
- 3rd side (hint)
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How do light microscopes work?
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They use glass lenses to refract light and produce a magnified image
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How do you calculate the magnification of a light microscope?
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Multiply the magnification of the eye piece lens by the objective lens
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🔬x🔭
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When were light microscopes and electron microscopes invented?
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Light microscopes; early 17th century
Electron microscopes; 1930s |
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How do electron microscopes work?
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They shine a beam of electrons through a sample. The wavelength of electrons is much smaller than the wavelength of light, so it is magnified more and reveals more detail.
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What features are found in bacterial cells?
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Cytoplasm
Cell wall Plasmid DNA Chromosomal DNA Flagella |
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What are chromosomes, and how many pairs do human cells have?
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Long coiled molecules of DNA, 23
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What is a gene?
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A section of DNA, which codes for a particular protein
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What does a DNA molecule consist of?
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2 strands, which are coiled to form a double helix. The strands are linked by a series of paired complementary bases;
Adenine - Thymine Cytosine - Guanine |
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What holds the bases of DNA together?
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Weak hydrogen bonds
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Who discovered the double helix model of DNA? When and where?
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James Watson and Francis Crick at Cambridge University in 1953
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What is genetic engineering?
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Removing a gene from one organism and inserting it into another. This can include animals, plants and microorganisms
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What are transgenic animals?
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Animals that have been genetically modified by having genes from another species inserted into their species
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How has rice been genetically modified? 🍚
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To contain a beta-carotene gene to reduce Vitamin A deficiency in humans. In the countries where vitamin A deficiency occurs the most (Africa and South East Asia) rice is a staple food.
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How is insulin produced on a large scale?
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The human gene for insulin has been inserted into bacteria, which are then used to produce the hormone on a large scale to treat diabetics.
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How do scientists produce herbicide-resistant crops?
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1◽ Find a wild plant that is resistant to the herbicide
2◽Transfer the resistant gene to crop plant's DNA by a vector 3◽Allow crops to grow, treat with herbicide to kill weeds 3◽New plants are resistant to herbicide and are not killed |
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Why do the offspring produced by asexual reproduction have the same genes as the parent?
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They get their genes from one parent only, so they are clones of their parent
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What is mitosis?
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The division of a cell nucleus to produce two cell nuclei with genetically identical sets of chromosomes
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Why does mitosis happen?
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to produce new cells for growth, to repair damaged tissues and in asexual reproduction
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What are clones? 🐏🐏🐏🐏🐏
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Individuals that are genetically identical
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What is differentiation?
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The process by which cells become specialised to allow them to perform a particular job efficiently
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What's special about stem cells?
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They are undifferentiated (unspecialised), which means they could, theoretically, differentiate into any type of cell
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What is a potential use of stem cells?
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They could be used to replace damaged cells as tissues to help in the treatment of diseases or injuries
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How are stem cells made to develop into other cells?
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By adding different chemicals, called growth factors, they are made to develop into:
▫insulin-producing cells in the pancreas ▫heart muscle cells ▫blood cells ▫neurones (nerve cells) ▫bone marrow cells |
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When does a person develop Parkinson's disease?
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When the neurones in the brain stop producing dopamine, a chemical that the neurones use to communicate with each other. When dopamine is not produced, the brain is unable to coordinate the movements of the body (amongst other things)
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How could stem cells be used as a potential cure for Parkinson's disease?
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If stem cells could be made into brain neurones and made to produce dopamine, this could provide a cure for the disease.
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Where can stem cells come from?
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▫Bone marrow
▫Embryos (embryonic stem cells) |
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What factors can make DNA mutations?
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▫UV radiation
▫viruses ▫some chemicals ▫errors during DNA replication |
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What are enzymes?
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▫Biological catalysts
▫They are protein molecules, which control the rate of chemical reactions that occur in living organisms |
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